1. Field of Invention
The present invention relates to a method of manufacturing a thin-film magnetic head having a thin-film magnetic head element and a plurality of electrodes for electrically connecting the element to an external device.
2. Description of Related Art
Performance improvements in thin-film magnetic heads have been sought with an increase in surface recording density of a hard disk drive. A composite thin-film magnetic head has been widely used which is made of a layered structure including a recording head (which may be called a recording element in the following description) having an induction magnetic transducer for writing and a reproducing head having a magnetoresistive (MR) element for reading. MR elements include an anisotropic magnetoresistive (AMR) element that utilizes the AMR effect and a giant magnetoresistive (GMR) element that utilizes the GMR effect. A reproducing head using an AMR element is called an AMR head or simply an MR head. A reproducing head using a GMR element is called a GMR head. An AMR head is used as a reproducing head whose surface recording density is more than 1 gigabit per square inch. A GMR head is used as a reproducing head whose surface recording density is more than 3 gigabits per square inch.
In general, an AMR film is made of a magnetic substance that exhibits the MR effect and has a single-layer structure. In contrast, many of GMR films have a multilayer structure. There are several types of mechanisms of producing the GMR effect. The layer structure of a GMR film depends on the mechanism. GMR films include a superlattice GMR film, a spin valve film and a granular film. The spin valve film is most efficient since the film has a relatively simple structure, exhibits a great change in resistance in a low magnetic field, and suitable for mass production.
Besides selection of a material as described above, the pattern width such as the MR height, in particular, is one of the factors that determine the performance of a reproducing head. The MR height is the length (height) between the end of an MR element closer to the air bearing surface (medium facing surface) and the other end. The MR height is basically controlled by an amount of lapping when the air bearing surface is processed.
Performance improvements in a recording head have been expected, too, with performance improvements in a reproducing head. It is required to increase the track density of a magnetic recording medium in order to increase the recording density among the performances of a recording head. In order to achieve this, a recording head of a narrow track structure has been desired to be manufactured by processing the magnetic pole into the submicron order through the use of semiconductor process techniques. The magnetic pole made of a magnetic material having high saturation flux density has been desired in order to achieve the narrow-track recording head.
Another factor determining the recording head performance is the throat height. The throat height is the length (height) of the portion (called a pole portion in the present invention) between the air bearing surface and the edge of the insulating layer electrically isolating the thin-film coil. A reduction in throat height is desired in order to improve the recording head performance. The throat height is also controlled by an amount of lapping when the air bearing surface is processed.
As thus described, it is important to fabricate a recording head and a reproducing head appropriately balanced so as to improve performance of a thin-film magnetic head.
The manufacturing process of a thin-film magnetic head includes a wafer process for forming thin-film patterns on a wafer as a substrate and a lapping process for adjusting the throat height and the MR height by lapping. The wafer process includes a number of mask steps and steps of pattern formation by plating, sputtering, etching, and chemical mechanical polishing (CMP) and so on. The performance and characteristics of the thin-film magnetic head may be modified by changing the track width of the reproducing element and the track width of the recording element and so on. Therefore, thin-film magnetic heads that meet a variety of needs of customers may be manufactured by determining the track width of the reproducing element and that of the recording element and so on, using masks that satisfy required specifications.
The manufacturing process of a thin-film magnetic head includes a number of steps and it takes an extremely long period of time to manufacture one product. Therefore, in order to manufacture the magnetic head having the performance and characteristics that meet the needs of the customer, it is required to carefully work out a detailed production plan so that the performance and characteristics of the magnetic head may be changed by photomask selection.
However, the needs of the customers are not limited to those relating to the performance and characteristics of the thin-film magnetic head that are determined in the wafer process but embrace the needs relating to a slider for retaining the magnetic head element and flying over the surface of a hard disk platter. The needs of the customers for a slider may be, for example, whether to choose a side element type slider or a center element type slider. The side element type slider is a slider wherein a thin-film magnetic head element is formed near an end of the slider in the direction orthogonal to the direction of air flow. The center element type slider is a slider wherein a thin-film magnetic head element is formed in the center of the slider in the direction orthogonal to the direction of air flow. The side element type slider and the center element type slider are typical sliders. In these days sliders are tend to be largely categorized into the above two types for satisfying the demand for the floating characteristics over the surface of the hard disk platter.
Reference is now made to FIG. 25 to FIG. 28 for describing the side element type slider and the center element type slider.
FIG. 25 is a schematic front view of a surface of the side element type slider in which a thin-film magnetic head element is formed. FIG. 26 is a schematic bottom view of the air bearing surface of the side element type slider. In FIG. 26 the arrow indicated with numeral 120 shows the direction of air flow. xe2x80x98LExe2x80x99 indicates the air inflow end. xe2x80x98TRxe2x80x99 indicates the air outflow end. In the side element type slider, as shown in FIG. 25 and FIG. 26, a thin-film magnetic head element 111 is formed near an end of the slider in the direction orthogonal to the direction of air flow, in the vicinity of an end face (end face of air outflow end TR in this example) 110 orthogonal to the direction of air flow. On the end face 110, four pad-shaped electrodes 112 are provided for electrically connecting the magnetic head element 111 to an external device. The four electrodes 112 are connected to the magnetic head element 111 through four conductors 113. A rail 115 is formed in the air bearing surface of the slider.
FIG. 27 is a schematic front view of a surface of the center element type slider in which a thin-film magnetic head element is formed. FIG. 28 is a schematic bottom view of the air bearing surface of the center element type slider. Numeral 120, xe2x80x98LExe2x80x99 and xe2x80x98TRxe2x80x99 of FIG. 28 are similar to those of FIG. 26. In the center element type slider, as shown in FIG. 27 and FIG. 28, the thin-film magnetic head element 111 is formed in the middle of the slider in the direction orthogonal to the direction of air flow, in the vicinity of an end face (end face of air outflow end TR in this example) 110 orthogonal to the direction of air flow. On the end face 110, the four pad-shaped electrodes 112 are provided for electrically connecting the magnetic head element 111 to an external device. The four electrodes 112 are connected to the magnetic head element 111 through the four conductors 113. The rail 115 is formed in the air bearing surface of the slider.
However, it is impossible to change between the side element type slider and the center element type slider by simply changing a photomask in an intermediate step in the manufacturing process of the thin-film magnetic head. It is therefore required in related-art techniques to prepare different sets of masks for the respective types of sliders and separately manufacture the sliders in volume.
In a hard disk drive for high density recording, a plurality of hard disk platters such as four or six platters are placed on top of one another. FIG. 29 illustrates an arrangement of thin-film magnetic heads in such a hard disk drive using a plurality of platters. A plurality of hard disk platters 122 are held by a rotating axis 121 in such a hard disk drive. The hard disk drive includes a thin-film magnetic head (called an up-type magnetic head in the following description) 123, placed beneath the platter 122, whose medium facing surface faces upward; and a thin-film magnetic head (called a down-type magnetic head in the following description) 124, placed above the platter 122, whose medium facing surface faces downward. The up-type magnetic head 123 and the down-type magnetic head 124 are coupled to a moving arm 125 through a suspension 126. The structural difference between the up-type magnetic head 123 and the down-type magnetic head 124 is the difference in position of the reproducing element and the recording element.
Accordingly, two kinds of thin-film magnetic heads, that is, the up-type head and the down-type head are required for each of the side element type slider and the center element type slider. The total of four kinds of thin-film magnetic heads are thus required. In the related art different sets of masks for twenty to thirty mask processing steps are prepared for each kind of magnetic head and magnetic heads of each kind are produced in volume. In a planned production, different mass-production lots are prepared for the respective kinds of magnetic heads for manufacturing magnetic heads that meet the customer""s needs.
In the related art thus described, thin-film magnetic heads are produced, using different masks or different mass-production lots for the respective kinds of magnetic heads. As a result, a cycle time, that is, a period of time between an order and a shipment is long and manufacturing costs are raised.
In particular, modifications and improvements in specifications of hard disk drives are made in a short period of time in these days. The customers of thin-film magnetic heads therefore demand that the magnetic heads that meet desired specifications are supplied shortly after the order. Consequently, the manufacturer of thin-film magnetic heads is required to manufacture a variety of products in small quantities that meet specifications demanded by the customers in a short period of time. The above-mentioned problems are therefore noticeable.
Where the related-art techniques are used, there are many cases in which specifications required by the customer are modified in the course of mass-production of thin-film magnetic heads meeting the specifications and mass-production is required to be restarted from the first step. Consequently, waste results and manufacturing costs are raised.
Where the related-art techniques are used, the manufacturer of thin-film magnetic heads estimates the number of products to be ordered by the customer and specifications required and mass-produces magnetic heads prior to the order, in some cases, in order to strictly maintain the product shipping schedule of the customer or to beat the competitors by immediate delivery. However, the number of products ordered by the customer and specifications required may go far beyond the estimates of the manufacturer since the customer may quickly respond to the users"" needs. In such a case the manufacturer has to keep a number of undelivered stocks and to produce new mass-production lots that meet the demand of the customer extremely quickly, regardless of the average cycle time. Since the specifications required by the customer or those of a final product change every six months, for example, in these days, undelivered products in stock for a couple of months are equivalent to nonconforming stocks to be wasted. Mass-production disregarding the average cycle time affects the balance of the mass-production line and reduces the mass-production capacities.
In Japanese Patent Application Laid-open Sho 61-296518(1986) and Japanese Patent Application Laid-open Hei 3-95715(1991), a techniques is disclosed for forming a slider having two head elements, a plurality of terminals common to the two head elements, and a plurality of conductors for connecting the head elements to the terminals. Some of the conductors connecting one of the head elements that is not used to the terminals are then cut off. However, the technique requires a step of cutting off the conductors in the manufacturing process of the thin-film magnetic head and the number of steps increases.
In Japanese Patent Application Laid-open Hei 6-203330(1994), a technique is disclosed for fabricating a slider having two head elements, one terminal commonly used for the two head elements, and two terminals corresponding to the respective two head elements. However, the technique requires the terminals for the respective head elements that are not commonly used for the head elements. It is therefore difficult to reduce the size of the thin-film magnetic head.
It is an object of the invention to provide a method of manufacturing a thin-film magnetic head for providing a thin-film magnetic head that meets specifications required by the customer in a short period of time and reducing manufacturing costs.
A thin-film magnetic head of the invention comprises: a main body wherein a thin-film magnetic head element is to be formed; a plurality of thin-film magnetic head element portions formed in the main body, each including a main part of the thin-film magnetic head element; a plurality of electrodes, formed in the main body, for electrically connecting any of the element portions to an external device; and a plurality of conductors, formed in the main body, provided only between selected one of the element portions and the electrodes, for electrically connecting the selected one of the element portions to the electrodes.
According to the thin-film magnetic head of the invention, selected one of the element portions is electrically connected to the electrodes through the conductors. As a result, thin-film magnetic heads of several types of specifications may be selectively provided.
In the thin-film magnetic head of the invention the thin-film magnetic element portions may each include: first and second magnetic layers magnetically coupled to each other and each made up of at least one layer and including pole portions placed in regions of the magnetic layers on a side of surfaces thereof facing a recording medium, the pole portions being opposed to each other; a gap layer placed between the pole portion of the first magnetic layer and the pole portion of the second magnetic layer; and a thin-film coil at least part of which is placed between the first and second magnetic layers, the part of the coil being insulated from the first and second magnetic layers. In addition, the conductors may be connected to the thin-film coil.
In the thin-film magnetic head of the invention the thin-film magnetic head element portions may each comprise a magnetoresistive element and the conductors may be connected to the magnetoresistive element.
The thin-film magnetic head of the invention may further comprise intermediate connecting portions, provided for the respective thin-film magnetic head element portions and connected to the element portions, to which the conductors are selectively connected.
In the thin-film magnetic head the main body may include a surface facing a recording medium and part of each of the element portions may be placed in the surface facing the recording medium.
A method of manufacturing a thin-film magnetic head of the invention includes the steps of: forming a plurality of thin-film magnetic head element portions in a section to be a main body wherein a thin-film magnetic head element is to be formed in a substrate, the element portion each including a main part of the thin-film magnetic head element; forming a plurality of electrodes, in the section to be the main body, for electrically connecting any of the element portions to an external device; and forming a plurality of conductors only between selected one of the element portions and the electrodes, in the section to be the main body, for electrically connecting selected one of the element portions to the electrodes.
According to the method of manufacturing a thin-film magnetic head of the invention, selected one of the element portions is electrically connected to the electrodes through the conductors. As a result, thin-film magnetic heads of several types of specifications may be selectively provided.
In the method the step of forming the electrodes may be performed either before or after the step of forming the conductors.
In the method the thin-film magnetic element portions may each include: first and second magnetic layers magnetically coupled to each other and each made up of at least one layer and including pole portions placed in regions of the magnetic layers on a side of surfaces thereof facing a recording medium, the pole portions being opposed to each other; a gap layer placed between the pole portion of the first magnetic layer and the pole portion of the second magnetic layer; and a thin-film coil at least part of which is placed between the first and second magnetic layers, the part of the coil being insulated from the first and second magnetic layers. In addition, the conductors may be connected to the thin-film coil.
In this case, in the method of the invention, the step of forming the element portions includes the steps of: forming the first magnetic layer, forming the gap layer on the pole portion of the first magnetic layer; forming the thin-film coil on the first magnetic layer, the coil being insulated from the first magnetic layer; and forming the second magnetic layer on the gap layer and the thin-film coil, the second magnetic layer being insulated from the coil.
In the method the thin-film magnetic head element portions may each comprise a magnetoresistive element. The conductors may be connected to the magnetoresistive element.
The method may further include, before the step of forming the conductors, the step of forming intermediate connecting portions for the respective thin-film magnetic head element portions, connected to the element portions, to which the conductors are selectively connected. The conductors may be connected to the intermediate connecting portions corresponding to selected one of the element portions.
In the method the main body may include a surface facing a recording medium and part of each of the element portions may be placed in the surface facing the recording medium in the step of forming the element portions.
In the method, if the element portions each include the first and second magnetic layers, the gap layer and the thin-film coil, the step of forming the conductors may be performed simultaneously with the step of forming the thin-film coil or with the step of forming the second magnetic layer, or may be performed after the step of forming the second magnetic layer.
A thin-film magnetic head sub-structure of the invention comprises a plurality of thin-film magnetic head element portions formed in a section to be a main body wherein a thin-film magnetic head element is to be formed in a substrate, the element portions each having a main part of the thin-film magnetic head element, the element portions being selectively and electrically connected through a plurality of conductors to a plurality of electrodes providing electrical connection between any one of the element portions and an external device, the conductors being formed only between the one of the element portions and the electrodes.
According to the thin-film magnetic head sub-structure, selected one of the element portions is electrically connected to the electrodes through the conductors, using the sub-structure. As a result, thin-film magnetic heads of several types of specifications may be selectively manufactured.
The thin-film magnetic head sub-structure may further comprise the electrodes.
In the thin-film magnetic head sub-structure the thin-film magnetic element portions may each comprise at least part of an induction-type magnetic transducer having first and second magnetic layers magnetically coupled to each other and each made up of at least one layer and including pole portions placed in regions of the magnetic layers on a side of surfaces thereof facing a recording medium, the pole portions being opposed to each other, a gap layer placed between the pole portion of the first magnetic layer and the pole portion of the second magnetic layer, and thin-film coil at least part of which is placed between the first and second magnetic layers, the part of the coil being insulated from the first and second magnetic layers.
In the thin-film magnetic head sub-structure the thin-film magnetic head element portions may each comprise a magnetoresistive element.
The thin-film magnetic head sub-structure may further comprise intermediate connecting portions, provided for the respective thin-film magnetic head element portions and connected to the element portions, to which the conductors are selectively connected.
In the thin-film magnetic head sub-structure the main body may include a surface facing a recording medium and part of each of the element portions may be placed in the surface facing the recording medium.
A method of manufacturing a thin-film magnetic head sub-structure of the invention includes the step of forming a plurality of thin-film magnetic head element portions formed in a section to be a main body wherein a thin-film magnetic head element is to be formed in a substrate, the element portions each having a main part of the thin-film magnetic head element, the element portions being selectively and electrically connected through a plurality of conductors to a plurality of electrodes providing electrical connection between any one of the element portions and an external device, the conductors being formed only between the one of the element portions and the electrodes.
According to the method of manufacturing a thin-film magnetic head sub-structure of the invention, a sub-structure comprising a plurality of element portions may be manufactured. Selected one of the element portions is electrically connected to the electrodes through the conductors, using the sub-structure. As a result, thin-film magnetic heads of several types of specifications may be selectively manufactured.
The method may further include the step of forming the electrodes.
In the method the thin-film magnetic element portions may each comprise at least part of an induction-type magnetic transducer having first and second magnetic layers magnetically coupled to each other and each made up of at least one layer and including pole portions placed in regions of the magnetic layers on a side of surfaces thereof facing a recording medium, the pole portions being opposed to each other, a gap layer placed between the pole portion of the first magnetic layer and the pole portion of the second magnetic layer, and thin-film coil at least part of which is placed between the first and second magnetic layers, the part of the coil being insulated from the first and second magnetic layers.
In the method the thin-film magnetic head element portions may each comprise a magnetoresistive element.
The method may further include the step of forming intermediate connecting portions for the respective thin-film magnetic head element portions, the connecting portions being connected to the element portions, the conductors being selectively connected to the connecting portions.
In the method the main body may include a surface facing a recording medium and part of each of the element portions may be placed in the surface facing the recording medium in the step of forming the element portions.
Other and further objects, features and advantages of the invention will appear more fully from the following description.